Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 12: Morphology Prediction at Interfaces
O 12.12: Vortrag
Montag, 7. März 2016, 17:45–18:00, S051
Hydroxylation and segregation induced morphology changes of MgO cube based nanostructures — Daniel Thomele1, Andreas Sternig2, Johannes Bernardi3, Simon Klacar4, Henrik Grönbeck4, and •Oliver Diwald1 — 1Department of Chemistry and Physics of Materials, University of Salzburg, Salzburg, Austria — 2Institute of Particle Technology, University of Erlangen-Nürnberg, Erlangen, Germany — 3University Service Center of Transmission Electron Microscopy, TU Vienna, Austria — 4Department of Applied Physics and Competence Centre for Catalysis, Chalmers University of Technology, Göteborg, Sweden
Vapor phase grown MgO cubes have turned out to be extremely valuable probes for the investigation of interface chemistry and particle morphology evolution inside powders. Comparative annealing experiments on these materials in dynamic high vacuum and in different gas atmospheres revealed the dramatic impact of residual water and surface hydroxylation on particle morphology and sintering properties. Moreover, we investigated the structural and energetic properties of Barium oxide (BaO) units dissolved inside the MgO host and adsorbed on MgO particle surfaces with HR Transmission Electron Microscopy and Density Functional Theory (DFT) calculations. The shape of BaO and MgO particles in a water environment were investigated as a function of temperature. The calculations suggest that the spherical shapes of the segregates result from the growth process and become thermodynamically stabilized by surface hydroxylation.